Tires are generally made from a composite of rubber compositions and fiber reinforcements made from textile materials such as synthetic polymers. It is important to achieve good adhesion between the textile material and the rubber composition in order to maintain the integrity of the tire. Power drive and under the hood hose applications also need to maintain integrity under high heat conditions.
Two adhesive systems which are widely used for achieving bonding between textile material and rubber compositions are: 1) the Resorcinol-Formaldehyde-Latex (RFL) coating method wherein an RFL adhesive is applied to the tire cord and 2) the Hexamethylenetetramine-Resorcinol or Hexamethoxymethylmelamine-Resorcinol adhesion promoting methods wherein an adhesion promotion system is incorporated into the rubber composition.
Resorcinol is a very expensive compound which exhibits very undesirable toxicological properties. Its use as a compound for the adhesion of textile materials to rubber is problematic because of its offensive odor, difficulty in handling and possible toxic hazards during rubber processing due to excess fuming of resorcinol during the curing or vulcanization process. U.S. Pat. Nos. 4,263,190 and 5,792,805 express the long held desire to reduce or eliminate the use of resorcinol in rubber processing.
The present invention partially relates to the partial replacement of resorcinol-formaldehyde in a RFL adhesive composition with an alkylated melamine-formaldehyde resin to reduce the amount of resorcinol in the RFL adhesive composition and provide similar or better adhesive characteristics to rubber.
U.S. Pat. No. 3,194,294 discloses the use of trimethylol melamine in a RFL adhesive composition to adhere nylon to natural rubber.
U.S. Pat. No. 4,263,190 discloses the use of mixture of an aklylated melamine-formaldehyde resin and a glyoxal-urea reaction product in latex to replace the use of resorcinol-formaldehyde resin in a RFL adhesive composition.
It is believed that none of the above-mentioned documents disclose or suggest the use of an alkylated melamine-formaldehyde resin in a RFL adhesive coating composition.